Asteroid Collision

If an object the size of the moon hits the earth a fifth of the planets land surface will vapourise. People, animals, plants and buildings will ignite. The blast will create a shockwave that will raze buildings on the rest of planet. Material ejected from the crater into the air will block out the sun. Most species on the planet will become extinct.

If an object twice the diameter of the moon hits the earth all life will be instantly vapourised. The earth will explode and fracture into pieces. The earth will no longer exist.